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[PATCH v52 08/10] Introduce an option to make logical replication database specific. 737+ messages / 2 participants [nested] [flat]
* [PATCH v52 08/10] Introduce an option to make logical replication database specific. @ 2026-04-03 10:34 Antonin Houska <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Antonin Houska @ 2026-04-03 10:34 UTC (permalink / raw) By default, the logical decoding assumes access to shared catalogs, so the snapshot builder needs to consider cluster-wide XIDs during startup. That in turn means that, if any transaction is already running (and has XID assigned), the snapshot builder needs to wait for its completion, as it does not know if that transaction performed catalog changes earlier. Possible problem with this concept is that if REPACK (CONCURRENTLY) is running in some database, backends running the same command in other databases get stuck until the first one has committed. Thus only as single backend in the cluster can run REPACK (CONCURRENTLY) at any time. Likewise, REPACK (CONCURRENTLY) can block walsenders starting on behalf of subscriptions throughout the cluster. This patch introduces the possibility for a backend to declare that its output plugin does not use shared catalogs (i.e. catalogs that can be changed by transactions running in other databases in the cluster). In that case, no snapshot the backend will use during the decoding needs to contain information about transactions running in other databases. Thus the snapshot builder only needs to wait for completion of transactions in the current database. Currently we only use this option in the REPACK background worker. It could possibly be used in walsender involved in logical replication too, however that would need thorough analysis of its output plugin. The patch bumps WAL version number, due to a new field in xl_running_xacts. --- contrib/pg_visibility/pg_visibility.c | 4 ++-- src/backend/access/index/genam.c | 18 ++++++++++++++++ src/backend/access/rmgrdesc/standbydesc.c | 2 ++ src/backend/access/transam/xlog.c | 2 +- src/backend/access/transam/xlogfuncs.c | 2 +- src/backend/commands/repack_worker.c | 8 +++++++ src/backend/postmaster/bgwriter.c | 2 +- src/backend/replication/logical/snapbuild.c | 10 ++++++++- src/backend/replication/slot.c | 12 +++++++++-- src/backend/storage/ipc/procarray.c | 23 ++++++++++++++++++++- src/backend/storage/ipc/standby.c | 14 +++++++++++-- src/include/access/genam.h | 8 +++++++ src/include/access/xlog_internal.h | 2 +- src/include/storage/procarray.h | 2 +- src/include/storage/standby.h | 3 ++- src/include/storage/standbydefs.h | 1 + 16 files changed, 99 insertions(+), 14 deletions(-) diff --git a/contrib/pg_visibility/pg_visibility.c b/contrib/pg_visibility/pg_visibility.c index dfab0b64cf5..d564bd2a00c 100644 --- a/contrib/pg_visibility/pg_visibility.c +++ b/contrib/pg_visibility/pg_visibility.c @@ -621,7 +621,7 @@ GetStrictOldestNonRemovableTransactionId(Relation rel) else if (rel == NULL || rel->rd_rel->relisshared) { /* Shared relation: take into account all running xids */ - runningTransactions = GetRunningTransactionData(); + runningTransactions = GetRunningTransactionData(InvalidOid); LWLockRelease(ProcArrayLock); LWLockRelease(XidGenLock); return runningTransactions->oldestRunningXid; @@ -632,7 +632,7 @@ GetStrictOldestNonRemovableTransactionId(Relation rel) * Normal relation: take into account xids running within the current * database */ - runningTransactions = GetRunningTransactionData(); + runningTransactions = GetRunningTransactionData(InvalidOid); LWLockRelease(ProcArrayLock); LWLockRelease(XidGenLock); return runningTransactions->oldestDatabaseRunningXid; diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c index 1408989c568..df092dc999a 100644 --- a/src/backend/access/index/genam.c +++ b/src/backend/access/index/genam.c @@ -37,6 +37,14 @@ #include "utils/ruleutils.h" #include "utils/snapmgr.h" +/* + * If a backend is going to do logical decoding and if the output plugin does + * not need to access shared catalogs, setting this variable to false can make + * the decoding startup faster. In particular, the backend will not need to + * wait for completion of already running transactions in other databases. + */ +bool accessSharedCatalogsInDecoding = true; + /* ---------------------------------------------------------------- * general access method routines @@ -394,6 +402,16 @@ systable_beginscan(Relation heapRelation, SysScanDesc sysscan; Relation irel; + /* + * If this backend promised that it won't access shared catalogs during + * logical decoding, this seems to be the right place to check. + * + * XXX Should this be ereport(ERROR) ? + */ + Assert(!HistoricSnapshotActive() || + accessSharedCatalogsInDecoding || + !heapRelation->rd_rel->relisshared); + if (indexOK && !IgnoreSystemIndexes && !ReindexIsProcessingIndex(indexId)) diff --git a/src/backend/access/rmgrdesc/standbydesc.c b/src/backend/access/rmgrdesc/standbydesc.c index 0a291354ae2..685d1bdb024 100644 --- a/src/backend/access/rmgrdesc/standbydesc.c +++ b/src/backend/access/rmgrdesc/standbydesc.c @@ -41,6 +41,8 @@ standby_desc_running_xacts(StringInfo buf, xl_running_xacts *xlrec) for (i = 0; i < xlrec->subxcnt; i++) appendStringInfo(buf, " %u", xlrec->xids[xlrec->xcnt + i]); } + + appendStringInfo(buf, "; dbid: %u", xlrec->dbid); } void diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 2c1c6f88b74..8da8eff93e4 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -7336,7 +7336,7 @@ CreateCheckPoint(int flags) * recovery we don't need to write running xact data. */ if (!shutdown && XLogStandbyInfoActive()) - LogStandbySnapshot(); + LogStandbySnapshot(InvalidOid); START_CRIT_SECTION(); diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c index 65bbaeda59c..0f5979691e6 100644 --- a/src/backend/access/transam/xlogfuncs.c +++ b/src/backend/access/transam/xlogfuncs.c @@ -245,7 +245,7 @@ pg_log_standby_snapshot(PG_FUNCTION_ARGS) (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("pg_log_standby_snapshot() can only be used if \"wal_level\" >= \"replica\""))); - recptr = LogStandbySnapshot(); + recptr = LogStandbySnapshot(InvalidOid); /* * As a convenience, return the WAL location of the last inserted record diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c85166ba849..ff34e246469 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -16,6 +16,7 @@ */ #include "postgres.h" +#include "access/genam.h" #include "access/table.h" #include "access/xlog_internal.h" #include "access/xlogutils.h" @@ -237,6 +238,13 @@ repack_setup_logical_decoding(Oid relid) EnsureLogicalDecodingEnabled(); + /* + * By declaring that our output plugin does not need shared catalogs, we + * avoid waiting for completion of transactions running in other databases + * than the one we're connected to. + */ + accessSharedCatalogsInDecoding = false; + /* * Neither prepare_write nor do_write callback nor update_progress is * useful for us. diff --git a/src/backend/postmaster/bgwriter.c b/src/backend/postmaster/bgwriter.c index 1d8947774a9..a30de4262eb 100644 --- a/src/backend/postmaster/bgwriter.c +++ b/src/backend/postmaster/bgwriter.c @@ -289,7 +289,7 @@ BackgroundWriterMain(const void *startup_data, size_t startup_data_len) if (now >= timeout && last_snapshot_lsn <= GetLastImportantRecPtr()) { - last_snapshot_lsn = LogStandbySnapshot(); + last_snapshot_lsn = LogStandbySnapshot(InvalidOid); last_snapshot_ts = now; } } diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index b4269a3b102..2e3926e1d13 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -125,6 +125,7 @@ #include <sys/stat.h> #include <unistd.h> +#include "access/genam.h" #include "access/heapam_xlog.h" #include "access/transam.h" #include "access/xact.h" @@ -1465,7 +1466,14 @@ SnapBuildWaitSnapshot(xl_running_xacts *running, TransactionId cutoff) */ if (!RecoveryInProgress()) { - LogStandbySnapshot(); + Oid dbid; + + /* + * Only consider transactions of the current database if our plugin is + * not supposed to access shared catalogs. + */ + dbid = accessSharedCatalogsInDecoding ? InvalidOid : MyDatabaseId; + LogStandbySnapshot(dbid); } } diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c index a9092fc2382..d553bd5dbff 100644 --- a/src/backend/replication/slot.c +++ b/src/backend/replication/slot.c @@ -39,6 +39,7 @@ #include <unistd.h> #include <sys/stat.h> +#include "access/genam.h" #include "access/transam.h" #include "access/xlog_internal.h" #include "access/xlogrecovery.h" @@ -1760,9 +1761,16 @@ ReplicationSlotReserveWal(void) if (!RecoveryInProgress() && SlotIsLogical(slot)) { XLogRecPtr flushptr; + Oid dbid; - /* make sure we have enough information to start */ - flushptr = LogStandbySnapshot(); + /* + * Make sure we have enough information to start. + * + * Only consider transactions of the current database if our plugin is + * not supposed to access shared catalogs. + */ + dbid = accessSharedCatalogsInDecoding ? InvalidOid : MyDatabaseId; + flushptr = LogStandbySnapshot(dbid); /* and make sure it's fsynced to disk */ XLogFlush(flushptr); diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c index cc207cb56e3..92ed34128e5 100644 --- a/src/backend/storage/ipc/procarray.c +++ b/src/backend/storage/ipc/procarray.c @@ -2631,9 +2631,11 @@ ProcArrayInstallRestoredXmin(TransactionId xmin, PGPROC *proc) * * Note that if any transaction has overflowed its cached subtransactions * then there is no real need include any subtransactions. + * + * If 'dbid' is valid, only gather transactions running in that database. */ RunningTransactions -GetRunningTransactionData(void) +GetRunningTransactionData(Oid dbid) { /* result workspace */ static RunningTransactionsData CurrentRunningXactsData; @@ -2708,6 +2710,18 @@ GetRunningTransactionData(void) if (!TransactionIdIsValid(xid)) continue; + /* + * Filter by database OID if requested. + */ + if (OidIsValid(dbid)) + { + int pgprocno = arrayP->pgprocnos[index]; + PGPROC *proc = &allProcs[pgprocno]; + + if (proc->databaseId != dbid) + continue; + } + /* * Be careful not to exclude any xids before calculating the values of * oldestRunningXid and suboverflowed, since these are used to clean @@ -2758,6 +2772,12 @@ GetRunningTransactionData(void) PGPROC *proc = &allProcs[pgprocno]; int nsubxids; + /* + * Filter by database OID if requested. + */ + if (OidIsValid(dbid) && proc->databaseId != dbid) + continue; + /* * Save subtransaction XIDs. Other backends can't add or remove * entries while we're holding XidGenLock. @@ -2791,6 +2811,7 @@ GetRunningTransactionData(void) * increases if slots do. */ + CurrentRunningXacts->dbid = dbid; CurrentRunningXacts->xcnt = count - subcount; CurrentRunningXacts->subxcnt = subcount; CurrentRunningXacts->subxid_status = suboverflowed ? SUBXIDS_IN_SUBTRANS : SUBXIDS_IN_ARRAY; diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c index de9092fdf5b..c653ea742bc 100644 --- a/src/backend/storage/ipc/standby.c +++ b/src/backend/storage/ipc/standby.c @@ -1188,6 +1188,14 @@ standby_redo(XLogReaderState *record) xl_running_xacts *xlrec = (xl_running_xacts *) XLogRecGetData(record); RunningTransactionsData running; + /* + * Records issued for specific database are not suitable for physical + * replication because that affects the whole cluster. In particular, + * the list of XID is probably incomplete here. + */ + if (OidIsValid(xlrec->dbid)) + return; + running.xcnt = xlrec->xcnt; running.subxcnt = xlrec->subxcnt; running.subxid_status = xlrec->subxid_overflow ? SUBXIDS_MISSING : SUBXIDS_IN_ARRAY; @@ -1277,11 +1285,12 @@ standby_redo(XLogReaderState *record) * as there's no independent knob to just enable logical decoding. For * details of how this is used, check snapbuild.c's introductory comment. * + * If 'dbid' is valid, only gather transactions running in that database. * * Returns the RecPtr of the last inserted record. */ XLogRecPtr -LogStandbySnapshot(void) +LogStandbySnapshot(Oid dbid) { XLogRecPtr recptr; RunningTransactions running; @@ -1314,7 +1323,7 @@ LogStandbySnapshot(void) * Log details of all in-progress transactions. This should be the last * record we write, because standby will open up when it sees this. */ - running = GetRunningTransactionData(); + running = GetRunningTransactionData(dbid); /* * GetRunningTransactionData() acquired ProcArrayLock, we must release it. @@ -1358,6 +1367,7 @@ LogCurrentRunningXacts(RunningTransactions CurrRunningXacts) xl_running_xacts xlrec; XLogRecPtr recptr; + xlrec.dbid = CurrRunningXacts->dbid; xlrec.xcnt = CurrRunningXacts->xcnt; xlrec.subxcnt = CurrRunningXacts->subxcnt; xlrec.subxid_overflow = (CurrRunningXacts->subxid_status != SUBXIDS_IN_ARRAY); diff --git a/src/include/access/genam.h b/src/include/access/genam.h index b69320a7fc8..56c573399ab 100644 --- a/src/include/access/genam.h +++ b/src/include/access/genam.h @@ -136,6 +136,14 @@ typedef struct IndexOrderByDistance bool isnull; } IndexOrderByDistance; +/* + * Is the backend interested in shared catalogs when performing logical + * decoding? + * + * XXX Is there a better place for this declaration? + */ +extern bool accessSharedCatalogsInDecoding; + /* * generalized index_ interface routines (in indexam.c) */ diff --git a/src/include/access/xlog_internal.h b/src/include/access/xlog_internal.h index 755835d63bf..ae19982d88d 100644 --- a/src/include/access/xlog_internal.h +++ b/src/include/access/xlog_internal.h @@ -31,7 +31,7 @@ /* * Each page of XLOG file has a header like this: */ -#define XLOG_PAGE_MAGIC 0xD11E /* can be used as WAL version indicator */ +#define XLOG_PAGE_MAGIC 0xD11F /* can be used as WAL version indicator */ typedef struct XLogPageHeaderData { diff --git a/src/include/storage/procarray.h b/src/include/storage/procarray.h index abdf021e66e..377b3060b9f 100644 --- a/src/include/storage/procarray.h +++ b/src/include/storage/procarray.h @@ -49,7 +49,7 @@ extern bool ProcArrayInstallImportedXmin(TransactionId xmin, VirtualTransactionId *sourcevxid); extern bool ProcArrayInstallRestoredXmin(TransactionId xmin, PGPROC *proc); -extern RunningTransactions GetRunningTransactionData(void); +extern RunningTransactions GetRunningTransactionData(Oid dbid); extern bool TransactionIdIsInProgress(TransactionId xid); extern TransactionId GetOldestNonRemovableTransactionId(Relation rel); diff --git a/src/include/storage/standby.h b/src/include/storage/standby.h index 6a314c693cd..8715c08e94f 100644 --- a/src/include/storage/standby.h +++ b/src/include/storage/standby.h @@ -126,6 +126,7 @@ typedef enum typedef struct RunningTransactionsData { + Oid dbid; /* only track xacts in this database */ int xcnt; /* # of xact ids in xids[] */ int subxcnt; /* # of subxact ids in xids[] */ subxids_array_status subxid_status; @@ -143,7 +144,7 @@ typedef RunningTransactionsData *RunningTransactions; extern void LogAccessExclusiveLock(Oid dbOid, Oid relOid); extern void LogAccessExclusiveLockPrepare(void); -extern XLogRecPtr LogStandbySnapshot(void); +extern XLogRecPtr LogStandbySnapshot(Oid dbid); extern void LogStandbyInvalidations(int nmsgs, SharedInvalidationMessage *msgs, bool relcacheInitFileInval); diff --git a/src/include/storage/standbydefs.h b/src/include/storage/standbydefs.h index 231d251fd51..e75b7078766 100644 --- a/src/include/storage/standbydefs.h +++ b/src/include/storage/standbydefs.h @@ -46,6 +46,7 @@ typedef struct xl_standby_locks */ typedef struct xl_running_xacts { + Oid dbid; /* only track xacts in this database */ int xcnt; /* # of xact ids in xids[] */ int subxcnt; /* # of subxact ids in xids[] */ bool subxid_overflow; /* snapshot overflowed, subxids missing */ -- 2.47.3 --gp2pyozrd5pweboh Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v52-0009-Reserve-replication-slots-specifically-for-REPAC.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-04 04:47 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-04 04:47 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: --- src/backend/commands/user.c | 246 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 191 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..6d8e2fa8813 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,92 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1181,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1263,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1274,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1582,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1681,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --xlWYagR37YwJXkF8-- ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --fotX2lJRknAHpfH+ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --cOHldBwZEf1OqVbN Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
* [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() @ 2026-07-06 08:28 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 737+ messages in thread From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw) DropRole() and GrantRole() resolve the role name to an OID before acquiring LockSharedObject() on the role. A concurrent session that commits a DROP ROLE between the read and the lock acquisition leaves the first session acting on a stale OID. This commit fixes the races by using the same approach as RangeVarGetRelidExtended(): It encapsulates name resolution, permission checking (via a caller-supplied callback), and lock acquisition inside a retry loop driven by SharedInvalidMessageCounter. If invalidation messages arrive between name resolution and locking, indicating concurrent DDL, the function retries. The lock is kept across retries and only released if the name resolves to a different OID on the next iteration. Two callbacks are provided: - RoleNameCallbackForDropRole(): checks current/session user, superuser attribute, and ADMIN OPTION privilege before locking. This is similar to what DropRole() is currently doing before LockSharedObject(). - RoleNameCallbackForGrantRole(): calls check_role_membership_authorization() to verify the current user can grant/revoke membership. This is similar to what GrantRole() is currently doing before calling AddRoleMems()/DelRoleMems(). DropRole() and GrantRole() now call RoleNameGetOid() with appropriate lock levels. AlterRole() does not need the fix because it calls CatalogTupleUpdate() on the pg_authid tuple before AddRoleMems(), which blocks a concurrent DROP ROLE. Author: Bertrand Drouvot <[email protected]> Reviewed-by: Surya Poondla <[email protected]> Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg --- src/backend/commands/user.c | 248 ++++++++++++++++++++++++++---------- src/include/commands/user.h | 9 ++ 2 files changed, 193 insertions(+), 64 deletions(-) 95.5% src/backend/commands/ 4.4% src/include/commands/ diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c index be11c49f919..5b869e91c17 100644 --- a/src/backend/commands/user.c +++ b/src/backend/commands/user.c @@ -34,6 +34,7 @@ #include "miscadmin.h" #include "port/pg_bitutils.h" #include "storage/lmgr.h" +#include "storage/sinval.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/catcache.h" @@ -116,6 +117,10 @@ static void plan_recursive_revoke(CatCList *memlist, bool revoke_admin_option_only, DropBehavior behavior); static void InitGrantRoleOptions(GrantRoleOptions *popt); +static void RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); +static void RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); /* Check if current user has createrole privileges */ @@ -126,6 +131,94 @@ have_createrole_privilege(void) } +/* + * RoleNameGetOid + * Given a role name, look up its OID, lock it, and return the OID. + * + * This follows the same pattern as RangeVarGetRelidExtended(): + * name resolution, permission check (via callback), and lock acquisition are + * performed inside a retry loop. If invalidation messages arrive during the + * process (indicating concurrent DDL), we retry to ensure the name still + * resolves to the same OID. + * + * The callback is invoked before locking, giving callers a chance to check + * permissions. It receives the current rolename, the resolved OID, the + * previous OID (InvalidOid on first iteration), and a caller-supplied arg. + * If the callback raises an error, the function aborts without locking. + * + * If missing_ok is true and the role does not exist, returns InvalidOid. + * Otherwise, raises an error. + */ +Oid +RoleNameGetOid(const char *rolename, LOCKMODE lockmode, bool missing_ok, + RoleNameGetOidCallback callback, void *callback_arg) +{ + uint64 inval_count; + Oid roleid; + Oid oldroleid = InvalidOid; + bool retry = false; + + for (;;) + { + /* + * Remember the current invalidation count so we can detect concurrent + * DDL after locking. + */ + inval_count = SharedInvalidMessageCounter; + + /* Look up the role name */ + roleid = get_role_oid(rolename, true); + + if (!OidIsValid(roleid)) + { + if (retry) + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + if (!missing_ok) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + return InvalidOid; + } + + /* + * Invoke caller-supplied callback before locking. This is a good + * place to check permissions: we haven't taken the lock yet, but we + * know the OID we intend to lock. If concurrent DDL changes things, + * the callback will be invoked again on the next iteration. + */ + if (callback) + callback(rolename, roleid, oldroleid, callback_arg); + + /* + * If upon retry we get back the same OID, the invalidation messages + * did not change the final answer. So we're done. + * + * If we got a different OID, we've locked the role that used to have + * this name rather than the one that does now. Release the old lock. + */ + if (retry) + { + if (roleid == oldroleid) + break; + UnlockSharedObject(AuthIdRelationId, oldroleid, 0, lockmode); + } + + /* Lock the role */ + LockSharedObject(AuthIdRelationId, roleid, 0, lockmode); + + /* If no invalidation messages were processed, we're done */ + if (inval_count == SharedInvalidMessageCounter) + break; + + /* Something may have changed, retry */ + retry = true; + oldroleid = roleid; + } + + return roleid; +} + + /* * CREATE ROLE */ @@ -1090,6 +1183,59 @@ AlterRoleSet(AlterRoleSetStmt *stmt) } +/* + * Before acquiring a role lock for DROP ROLE, check that the role is not the + * current/session user and that the caller has sufficient privileges to drop it. + */ +static void +RoleNameCallbackForDropRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + HeapTuple tuple; + Form_pg_authid roleform; + + if (roleid == GetUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetOuterUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("current user cannot be dropped"))); + if (roleid == GetSessionUserId()) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + errmsg("session user cannot be dropped"))); + + tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid)); + if (!HeapTupleIsValid(tuple)) + ereport(ERROR, + (errcode(ERRCODE_UNDEFINED_OBJECT), + errmsg("role \"%s\" does not exist", rolename))); + + roleform = (Form_pg_authid) GETSTRUCT(tuple); + + /* + * For safety's sake, we allow createrole holders to drop ordinary roles + * but not superuser roles, and only if they also have ADMIN OPTION. + */ + if (roleform->rolsuper && !superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", + "SUPERUSER", "SUPERUSER"))); + if (!is_admin_of_role(GetUserId(), roleid)) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("permission denied to drop role"), + errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", + "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); + + ReleaseSysCache(tuple); +} + + /* * DROP ROLE */ @@ -1119,9 +1265,7 @@ DropRole(DropRoleStmt *stmt) { RoleSpec *rolspec = lfirst(item); char *role; - HeapTuple tuple, - tmp_tuple; - Form_pg_authid roleform; + HeapTuple tmp_tuple; ScanKeyData scankey; SysScanDesc sscan; Oid roleid; @@ -1132,71 +1276,27 @@ DropRole(DropRoleStmt *stmt) errmsg("cannot use special role specifier in DROP ROLE"))); role = rolspec->rolename; - tuple = SearchSysCache1(AUTHNAME, PointerGetDatum(role)); - if (!HeapTupleIsValid(tuple)) - { - if (!stmt->missing_ok) - { - ereport(ERROR, - (errcode(ERRCODE_UNDEFINED_OBJECT), - errmsg("role \"%s\" does not exist", role))); - } - else - { - ereport(NOTICE, - (errmsg("role \"%s\" does not exist, skipping", - role))); - } + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP or ALTER commits between name + * resolution and lock acquisition. + */ + roleid = RoleNameGetOid(role, AccessExclusiveLock, stmt->missing_ok, + RoleNameCallbackForDropRole, NULL); + if (!OidIsValid(roleid)) + { + /* missing_ok case: role doesn't exist */ + ereport(NOTICE, + (errmsg("role \"%s\" does not exist, skipping", + role))); continue; } - roleform = (Form_pg_authid) GETSTRUCT(tuple); - roleid = roleform->oid; - - if (roleid == GetUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetOuterUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("current user cannot be dropped"))); - if (roleid == GetSessionUserId()) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_IN_USE), - errmsg("session user cannot be dropped"))); - - /* - * For safety's sake, we allow createrole holders to drop ordinary - * roles but not superuser roles, and only if they also have ADMIN - * OPTION. - */ - if (roleform->rolsuper && !superuser()) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute may drop roles with the %s attribute.", - "SUPERUSER", "SUPERUSER"))); - if (!is_admin_of_role(GetUserId(), roleid)) - ereport(ERROR, - (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), - errmsg("permission denied to drop role"), - errdetail("Only roles with the %s attribute and the %s option on role \"%s\" may drop this role.", - "CREATEROLE", "ADMIN", NameStr(roleform->rolname)))); - /* DROP hook for the role being removed */ InvokeObjectDropHook(AuthIdRelationId, roleid, 0); - /* Don't leak the syscache tuple */ - ReleaseSysCache(tuple); - - /* - * Lock the role, so nobody can add dependencies to her while we drop - * her. We keep the lock until the end of transaction. - */ - LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock); - /* * If there is a pg_auth_members entry that has one of the roles to be * dropped as the roleid or member, it should be silently removed, but @@ -1484,6 +1584,21 @@ RenameRole(const char *oldname, const char *newname) return address; } +/* + * Before acquiring a role lock for GRANT/REVOKE, check that the current user + * has authorization to grant/revoke membership in the specified role. + */ +static void +RoleNameCallbackForGrantRole(const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg) +{ + bool is_grant = *((bool *) callback_arg); + Oid currentUserId = GetUserId(); + + check_role_membership_authorization(currentUserId, roleid, is_grant); +} + + /* * GrantRoleStmt * @@ -1568,9 +1683,14 @@ GrantRole(ParseState *pstate, GrantRoleStmt *stmt) (errcode(ERRCODE_INVALID_GRANT_OPERATION), errmsg("column names cannot be included in GRANT/REVOKE ROLE"))); - roleid = get_role_oid(rolename, false); - check_role_membership_authorization(currentUserId, - roleid, stmt->is_grant); + /* + * Use RoleNameGetOid to resolve the name, check permissions, and lock + * the role atomically with a retry loop. This prevents race + * conditions where a concurrent DROP commits between name resolution + * and lock acquisition. + */ + roleid = RoleNameGetOid(rolename, ShareUpdateExclusiveLock, false, + RoleNameCallbackForGrantRole, &stmt->is_grant); if (stmt->is_grant) AddRoleMems(currentUserId, rolename, roleid, stmt->grantee_roles, grantee_ids, diff --git a/src/include/commands/user.h b/src/include/commands/user.h index 97dcb93791b..17263452250 100644 --- a/src/include/commands/user.h +++ b/src/include/commands/user.h @@ -21,6 +21,15 @@ extern PGDLLIMPORT int Password_encryption; /* values from enum PasswordType */ extern PGDLLIMPORT char *createrole_self_grant; +/* Callback for RoleNameGetOid, invoked after name resolution but before locking */ +typedef void (*RoleNameGetOidCallback) (const char *rolename, Oid roleid, + Oid oldroleid, void *callback_arg); + +extern Oid RoleNameGetOid(const char *rolename, LOCKMODE lockmode, + bool missing_ok, + RoleNameGetOidCallback callback, + void *callback_arg); + /* Hook to check passwords in CreateRole() and AlterRole() */ typedef void (*check_password_hook_type) (const char *username, const char *shadow_pass, PasswordType password_type, Datum validuntil_time, bool validuntil_null); -- 2.34.1 --Dvg/WemKV0I3T/Od Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0002-Protect-role-resolution-in-roleSpecsToIds-against.patch" ^ permalink raw reply [nested|flat] 737+ messages in thread
end of thread, other threads:[~2026-07-06 08:28 UTC | newest] Thread overview: 737+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2026-04-03 10:34 [PATCH v52 08/10] Introduce an option to make logical replication database specific. Antonin Houska <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-04 04:47 [PATCH v1] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v2 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v4 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]> 2026-07-06 08:28 [PATCH v3 1/2] Add RoleNameGetOid() with invalidation-based retry loop for DropRole()/GrantRole() Bertrand Drouvot <[email protected]>
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